Propeller barrel

ABSTRACT

A novel propeller barrel is provided by a structure in which major centrifugal loads and bending moments are reacted efficiently in tension or compression members, such as largediameter, thin-section tubes, rather than inefficiently in bending members as in conventional propeller barrels. The invention herein described was made in the course of or under a contract or subcontract thereunder with the Department of the Army.

United States Patent ma l .04 N064 wwm 714 1,777,678 10/1930 Rieseler et al. 2,083,439 6/1937 Fedden et al. 2,491,862 12/1949 Klos............ 3,156,302 11/1964 Jordan.........................,

[72] Inventor Philip E. Barnes North Granby, Conn.

[2 1] Appl. No. 790,702

[22] Filed Jan. 13, 1969 [45] Patented June 15, 1971 FOREIGN PATENTS 15/1943 ltaly [73] Assignee United Aircraft Corporation East Hartford, Conn.

[54] PROPELLER BARREL 3 Claims, 5 Drawing Figs.

ABSTRACT: A novel propeller barrel is provided by a struc- [51] lnt.Cl................. [50] FieldofSearch......

ture in which major centrifugal loads and bending moments are reacted efficiently in tension or compression members,

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m A e t f o t n e m t r a P m 44 44 HU 66 11 .44/ 6. 4 h m w ew? TS 036 FHV 582 452 999 111 //l 602 11 203 46 808,H 753m 22 F/G.2 PRIOR ART AIENIED JUN] 5 ml F/G/ PRIOR ART S E N NW l H P lail-L Has" AGENT PROPELLER BARREL BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to propeller barrel structures and particularly to one-piece, lightweight, high-strength propeller barrel structures.

2. Description of the Prior Art A well-known type of propeller barrel structure is shown in FIG. 1, and a schematic showing the load path of the forces acting on the barrel structure is shown in FIG. 2. Referring to FIG. 1, conventional barrel structures consist basically of ring structures l0, l2 and 16 which support cylindrical blade arms 14. Ring or body structure 16 is blended between the blade arms 14 and the rings and 12 to make a closed structure. As can be seen from FIG. 2, the centrifugal blade loads acting on the barrel are reacted in bending as shown by the dotted lines. In order to react this bending stress, the structure must be comprised of thick section; and, as will be obvious to one skilled in the art, the conventional propeller barrel is, therefore, inherently of great weight.

SUMMARY OF THE INVENTION which reacts major centrifugal blade loads and bending moments in tension or compression members is provided by a propeller barrel structure in which there is provided the shortest possible load path from each blade arm to the opposing blade arms. This eliminates the necessity of carrying the loads in rings around to the other blades as is done presently in conventional propeller barrels. This is accomplished by carrying the blade supporting arms across to each other, forming either a continuous cylinder or a balanced truss-type structure in which each blade arm is disposed directly on the opposing blade arms as shown in FIG. 3 and FIG. 5, respectively. By carrying the blade supporting arms across to each other, major loads are reacted efficiently in tension or compression rather than inefficiently in bending, thus resulting in a lower weight structure.

In further accordance with the present invention, moment loads are reacted more efficiently than accomplished heretofore by a structure in which the wall thickness of the blade supporting arm is no greater than ten percent of the blade supporting arm diameter. As will be understood by those skilled in the art, moment loads will be reacted more efficiently in a thin-wall structure than in the conventional heavy-walls, small-diameterstructures.

The foregoing and other objects, features and advantages of I the present invention will become more apparent in light of the following detailed description of a preferred embodiment thereof, as illustrated in the accompanying drawings.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a conventional propeller barrel structure well known in the art.

FIG. 2 is a schematic illustration of the load path of the forces acting on the structure of FIG. 1 showing that the forces are reacted in bending.

FIG. 3 is a perspective view of an exemplary embodiment of a propeller barrel structure in accordance with the present invention.

FIG. 4 is a schematic illustration showing the load path of the forces acting on the structure in FIG. 3 showing that the forces are reacted in tension or compression rather than the bending.

FIG. 5 is a schematic illustration of another exemplary embodiment of a propeller barrel structure in accordance with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 3, there is shown a rear housing 18 which may be essentially cone-shaped, having disposed thereon two crossed cylinders 20 and 22. As shown, each cylinder is continuous and passes through the other cylinder. The ends of the cylinders 24, 26, 28 and 30 form the blade supporting arms and are adapted to form sockets for the propeller blades (not shown) in any manner well known in the art. In FIG. 4 it will be'seen that the centrifugal blade loads, as represented by the arrows 32, are reacted in tension as shown by the phantom extensions 34 of the cylinders 20 and 22. It will be noted in comparing the load path shown in FIG. 4 with the load path shown in FIG. 2 that the load path in FIG. 4 does not go around a ring from one blade arm to the next. But rather the load from one blade is reacted equally and oppositely through the cylinder to the opposite blade arm. In FIG. 2 it can be seen that in addition to the centrifugal blade load being taken somewhat in tension, as represented by the phantom extension 36 of the blade arm 14, there is also bending of the ring 16 as shown by the phantom lines 38. As has been explained heretofore, it is a disadvantage to react major blade loads in bending since the structure must be of a much greater size and weight to react the bending loads than it would be if the loads are taken completely in tension or compression.

FIG. 5 shows another embodiment of the present invention in which the propeller is a three-way propeller. In this case the barrel structure is comprised of three blade supporting arms 40, 42, and 44 being arranged in a truss-type structure as will be obvious to those skilled in the art. Again in this type structure, the major blade loads are taken in tension or compression rather than in bending. In addition, there is also shown on the drawing depicting this embodiment another aspect of the invention, which is to react moment loads more efficiently than is done in the propeller barrels known in the art. The wall thickness of the blade supporting arms is shown to be no greater than 10 percent of the blade supporting arm diameter.

There has thus been described a preferred embodiment of a propeller barrel in accordance with the present invention. It should be understood by those skilled in the art that while four-way and three-way propeller barrels have been shown to describe a preferred embodiment of my invention, other propellers having any number of blades may utilize my invention. Furthermore, while I have shown blade supporting arms of generally cylindrical shape, they could also be of other shapes.

Iclaim:

l. A propeller barrel structure, comprising:

a rear housing having a central axis and a forward end and a rear end; and

a pair of hollow cylinders, one perpendicular to the other and each cylinder passing through and being continuous through the other cylinder, the wall thickness of said cylinders being less than lOpercent of the diameter of said cylinders, said cylinders disposed on the forward end of said housing so that the axes of said hollow cylinders are perpendicular to the axis of said housing and being in load reaction relation such that the bending and centrifugal loads imposed by said propeller are reacted substantially by tension and compression while being substantially free from bending reaction of said cylinders.

2. A propeller unitary barrel construction having a rotating axis for supporting three or more propeller blades, comprising a pair of cylindrical hollow members disposed about said rotating axis to receive the roots of said propeller blades,

by tension and compression while being substantially free from bending reactions within the unitary construction.

3. A propeller unitary barrel construction, as recited in claim 2, wherein each of said hollow cylindrical members have a wall thickness less than 10 percent of the diameter of the hollow cylindrical member. 

1. A propeller barrel structure, comprising: a rear housing having a central axis and a forward end and a rear end; and a pair of hollow cylinders, one perpendicular to the other and each cylinder passing through and being continuous through the other cylinder, the wall thickness of said cylinders being less than 10percent of the diameter of said cylinders, said cylinders disposed on the forward end of said housing so that the axes of said hollow cylinders are perpendicular to the axis of said housing and being in load reaction relation such that the bending and centrifugal loads imposed by said propeller are reacted substantially by tension and compression while being substantially free from bending reaction of said cylinders.
 2. A propeller unitary barrel construction having a rotating axis for supporting three or more propeller blades, comprising a pair of cylindrical hollow members disposed about said rotating axis to receive the roots of said propeller blades, said hollow cylindrical members intersecting each other and each hollow cylindrical member being continuous through the other hollow cylindrical member, each of said hollow cylindrical members having an extension portion extending inwardly toward said axis of rotation and being in load reaction relationship relative to each other so that the bending and centrifugal loads imposed by said propeller blades are reacted substantially by tension and compression while being substantially free from bending reactions within the unitary construction.
 3. A propeller unitary barrel construction, as recited in claim 2, wherein each of said hollow cylindrical members have a wall thickness less than 10 percent of the diameter of the hollow cylindrical member. 